Capital Gains Tax calculator for shares
For 2026/27, individuals usually have a £3,000 annual exempt amount. Taxable gains on ordinary shares are charged at 18% to the extent they fit in the unused basic-rate band and 24% above it.
Enter the allowable pooled cost you have already worked out under HMRC's share identification rules. This estimator does not perform same-day, 30-day or Section 104 matching, and it excludes employee shares, non-residents, trusts, Business Asset Disposal Relief and Investors' Relief.
How the calculation works
Sale proceeds minus allowable cost gives the gain. Current-year losses come off first, then the £3,000 annual exempt amount. Registered losses brought forward are used only against what remains in this focused calculation. The taxable gain fills any unused part of the £37,700 basic-rate band at 18%; the rest is charged at 24%.
Your taxable-income input is income after the Personal Allowance and other Income Tax reliefs. Do not enter gross salary. If you have several disposals or different asset types, work out the combined gains, losses and best use of the annual exempt amount before relying on an estimate.
| Taxable income | £20,000 |
|---|---|
| Gain before exemption | £52,600 |
| At 18% | £17,700 |
| At 24% | £31,900 |
| Capital Gains Tax | £10,842 |
The result reproduces the current worked example on GOV.UK Capital Gains Tax rates.
Getting the allowable cost right
Shares of the same class in the same company are not always matched to the oldest purchase first. HMRC may match shares bought on the same day, then shares bought in the following 30 days, before using the pooled Section 104 holding. Use the figure produced by those rules as “allowable cost” here.
Allowable incidental costs can include dealing fees and certain professional fees. ISA gains are tax free and should stay out of this calculator. Read HMRC's share-gain steps before entering a pooled cost.